1. Field of the Invention
The disclosure relates to a light emitting device.
2. Description of the Related Art
Light emitting devices using a semiconductor chip (light emitting element), such as a light emitting diode, have widely been used because of easy reduction in size and high light emission efficiency.
The light emitting devices using a semiconductor chip is classified into two major types, namely, a face-up type in which a pad electrode is mounted on a surface of the semiconductor chip located on the opposite side to a mounting substrate, and a face-down type in which an electrode is mounted on a lower surface of the semiconductor chip facing a mounting substrate.
In the face-up type device, the semiconductor chip is mounted on a lead or the like, and the semiconductor chip and the lead are connected together by bonding wires or the like. When mounting the semiconductor chip on a mounting substrate, parts of the bonding wires need to be positioned outside the semiconductor chip as viewed planarly from the direction perpendicular to the surface of the substrate, which limits the reduction in size.
On the other hand, in the face-down type device (in many cases, taking a flip-chip form), pad electrodes provided on the lower surface of a semiconductor chip can be electrically connected to a wiring provided on the mounting substrate by connection means, including bumps and metal pillars located on the inner side of the semiconductor chip as viewed planarly from the direction perpendicular to the surface of the mounting substrate.
Thus, the size of the light emitting device (particularly, the size as viewed planarly from the direction perpendicular to the mounting substrate) can be reduced as much as possible close to the size of the semiconductor chip, thereby achieving a chip size package (CSP).
Recently, in order to further progress the reduction in size or to further enhance the light emission efficiency, a face-down type light emitting device is used which is obtained by removing or thinning a growth substrate (translucent substrate) formed of sapphire or the like.
The growth substrate is a substrate used to grow thereon a p-type semiconductor layer and an n-type semiconductor layer forming a semiconductor chip. The growth substrate also has the effect of supporting the thin low-strength semiconductor chip to improve the strength of the light emitting device.
In a light emitting device produced by removing the growth substrate or in a light emitting device produced with the thinned growth substrate after forming the semiconductor chip (LED chip), for example, as disclosed in JP 2010-141176 A, a resin layer is provided on an electrode side (side facing the mounting substrate) for supporting the semiconductor chip, and metal pillars are formed to penetrate the resin layer. The electrode of the semiconductor chip is electrically connected to the wiring (wiring layer) provided on the mounting substrate by the metal pillars.
In this way, the light emitting device can ensure the sufficient strength by the formation of the resin layer including the metal pillars.